winfrom中datagridview为什么取值为空
datagridview.DataSource = dt;
textbox1.text=datagridview.Rows[0].Cells[0].Value.ToString();
textbox2.text=datagridview.SelectedRows[0].Cells[0].Value.ToString();
textbox3.text=datagridview.CurrentRow.Cells[1].Value.ToString();
textbox1,2,3都取值为空怎么回事?